Check valves are valves that allow fluid flow in one direction therethrough and prevent flow in the opposite direction. They are widely used in a range of applications, for example in air conditioning systems, for example in an aircraft system.
Check valves commonly include one or more valve elements or flappers located at an opening in a valve body. The flappers are hingedly supported relative to the valve body such that in a closed position they lie across and close the opening, preventing fluid flow through the opening in one direction. However, under the pressure of a fluid (gas or liquid) on one side of the check valve, the flappers rotate from their closed positions so as to allow the fluid to flow through the valve in the opposite direction.
Typical check valves often have one or more physical stops, which limit the angle to which the flappers may open. When the flappers move from the closed to the open position, the flappers hit the stop or stops, thereby preventing the flappers from opening further. In a known arrangement, the stop is provided by a pin which is mounted to posts arranged on opposite sides of the valve housing and which extends across the opening at a distance therefrom. One such arrangement is shown in EP-A-2034224.